The present invention relates generally to a flexible fuel system and more particularly to a flexible fuel sensor using a resonant electromagnetic cavity to determine fuel composition.
The interest in flexible fuel vehicles has increased dramatically in recent years. This is especially true with respect to vehicles capable of operating on blends of gasoline and alcohol.
In such vehicles, it is necessary to monitor the fuel mixture (e.g., the percentage by weight of alcohol) in order to adjust engine performance. The signal from the flexible fuel sensor is typically transmitted to and utilized by an electronic engine control to properly set spark timing, exhaust gas recirculation and fuel enrichment. The flexible fuel system plays a particularly important role during open-loop feedback conditions, i.e., cold start-up and wide-open throttle.
The flexible full sensors presently under investigation fall into two major categories: optical effect and dielectric effect. Optical sensors utilize the index of refraction or infrared absorption pattern of the fuel blend. Dielectric sensors operate upon a change in the dielectric constant of the fuel blend as the fuel mixture varies.